Last changes and cleaning in documentation

Closes #99 (closed)
This time I think it's perfect ! See details in the issue.
Sorry I pushed on develop yesterday, I had to test how the CI trigger work.

To summarize changes done here and in !78, !79 and !80 :

• better CI trigger : on tags or MR or protected branch, without duplicated executions (using example here )
• run tests and linters only when files changed
• jobs should run a bit faster with pip cache (because it's mostly time spent in pip install), without affecting how the test runs
• enhanced docs workflow
  • build docs on md or py changes (we can activate the manual trigger if this is too long and we only push python code)
  • readthedocs will pull changes for any commit in master or develop, we can also activate specific tags as done here
• auto ship to pypi for tags : creating a tag will trigger a pipeline with shipping, no matter the branch or if in MR
  • for tags semantic see https://peps.python.org/pep-0440/ ==> 2.0.0.devN is the standard for non release builds.
  • it will be flagged as pre-release e.g. https://pypi.org/project/pyotb/2.0.0.dev2/
  • then it should be installable via pip install --upgrade --pre pyotb